Non-Metallic, Multi-Strand Control Cable for Steerable Instruments

ABSTRACT

Embodiments of the invention provide methods for inserting a non-metallic multi-strand braid through a coil tube. Techniques for bonding one end of a lead line to one end of a multi-strand non-metallic braid are provided. There are also embodiments of steerable instruments described having a plurality of hinged segments; a multi-strand non-metallic braid connected distally to one segment of the plurality of segments and proximally to an actuator; and a steering controller adapted to control the actuator to move the hinged segment using the multi-strand non-metallic braid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/739,250 filed Nov. 23, 2005, titled, “Improved Tendon For SteerableInstruments” which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

One technique for transmitting actuation forces to the moveable segmentsof articulating instruments involves the use of a cable within a housingor a coil tube. This arrangement is commonly referred to as a Bowdencable and is similar in operation to a brake system on bicycle. Thiscable is used to transmit an actuation force from a control handle outto a steerable active segment. In some cases the forces needed tomaneuver a steerable instrument can be large. In some cases, the largeactuation force results from friction between the steel cable and thecoil tube. It is desirable to reduce the amount of force the frictionalforces in the cable/tube arrangement including the use of lubricantssuch as, for example, molybdenum disulfide.

However useful the lubricants may be, a number of practical challengesremain, such as, for example: (1) the molybdenum disulfide lubricant inpowder form will eventually wear out with use of the scope causingdegradation of scope performance; (2) the molybdenum disulfide lubricantis difficult to apply inside the coil and is messy during application;(3) the addition of any lubricant between cable and coil tube alsocauses lubrication issues between each of the coils of the coil tubeallowing them to slip over each other under compressive loads. Coil tubebuckling rapidly degrades endoscope performance and require expensiverebuilt of the scope coils.

What is needed is an improved way of overcoming the friction forcesassociated with transmitting actuation forces to the moveable segmentsof an articulating instrument. strand non-metallic braid whilemaintaining the diameter of the bonded area the same as or less than thediameter of either the non-metallic multi-strand braid or the lead line.Next, advance the multi-strand non-metallic braid through a coil tubeusing the lead line. In one alternative, the lead line is altered beforethe bonding step to improve adhesion to the non-metallic multi-strandbraid. In another alternative, the bonding step includes gluing one endof the lead line to one end of a multi-strand non-metallic braid. Inanother alternative, the bonding step includes thermally bonding one endof the lead line to one end of a multi-strand non-metallic braid. In oneaspect, a strand of the multi-strand braid is cut before the bondingstep. In another embodiment, before the bonding step, placing one end ofthe lead line and one end of the non-metallic multi-strand braid into afixture. In one aspect, the diameter of one end of the lead line or oneend of the non-metallic multi-strand braid is reduced before bonding thelead line and the non-metallic multi-strand braid. In one aspect, thelead line is formed from the same material as the non-metallicmulti-stranded braid.

In another aspect, the end of the multi-strand non-metallic braid isterminated. In one aspect, terminating includes forming a knot in themulti-strand non-metallic braid. In another aspect, the multi-strandnon-metallic braid is passed through a threaded element before theterminating step. Termination may be accomplished by applying anadhesive to the knot formed in the multi-strand non-metallic braid,gluing a ball within the multi-strand non-metallic braid, securing acrimp to the multi-strand non-metallic braid or forming a loop in oneend of the multi-strand non-metallic braid.

In another embodiment, there is provided a steerable instrument having aplurality of hinged segments; a multi-strand non-metallic braidconnected distally to one segment of the plurality of segments andproximally to an actuator; and a steering controller adapted to controlthe actuator to move the hinged segment using the multi-strandnon-metallic braid. In one aspect, a connector assembly couples themulti-strand non-metallic braid to the actuator. In another aspect,there is a carriage assembly in the connector and attached to one end ofthe multi-strand non-metallic braid. In another aspect, the multi-strandnon-metallic braid passes through a coil tube extending between theconnector assembly and the segment. In one alternative, the ratio of theclearance between the multi-strand non-metallic braid and the interiorsurface of the coil tube to the inner diameter of the coil tube is lessthan or equal to 15%. In one embodiment, the multi-strand non-metallicbraid comprises ultra high molecular weight polyethylene (UHMWPE). Inone aspect, the multi-strand non-metallic braid is connected distally toone segment of the plurality of segments by terminating the multi-strandnon-metallic braid at the desired segment. In another aspect, there is athreaded element on the one end of the multi-strand non-metallic braidto attach the one end of the multi-strand non-metallic braid to thecarriage assembly. In another aspect, there is a knot formed in themulti-strand non-metallic braid positioned between the threaded elementon the one end of the multi-strand non-metallic braid and the carriageassembly. In one embodiment, there is a knot formed in the multi-strandnon-metallic braid. In one aspect, there is an adhesive applied to theknot. In another aspect, the adhesive contains a pigment that provides avisual indication that the adhesive is present.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIGS. 1A, 1A1 and 1B illustrate various views of a fixture used to bonda leader to an braid structure.

FIG. 2 illustrates altering the end of a braid prior to bonding.

FIG. 3A and 3B illustrate different altered leaders.

FIG. 4 illustrates the fixture of FIGS. 1A-1B in a vise during a bondingoperation.

FIG. 5 illustrates a strand bonded to a leader being removed from afixture.

FIG. 6 illustrates the diameters of the leader, the braid and a bondedarea.

FIGS. 7A and 7B illustrate a cross section view of a braid in a coiltube.

FIG. 8 illustrates a braid connected to a segmented, hinged instrument.

FIG. 9 illustrates using the braid to articulate the instrument in FIG.8.

FIG. 10 shows a schematic view of a system for articulating acontrollable article or bendable instrument.

FIG. 11 is a perspective view of a connector assembly.

FIG. 12 illustrates an embodiment of a segmented endoscope.

FIG. 13 illustrates an embodiment of a system used with an instrument ofthe invention;

FIG. 14 shows a partial schematic representation of a single UHMWPEtendon connected to a segment and an actuator.

DETAILED DESCRIPTION OF THE INVENTION

The use of braided Ultra-High Molecular Weight Polyethylene (UHMWPE) isproposed as replacement for conventional stainless steel control cables.UHMWPE force transmissions cables may be used without additionallubrication. Our testing has demonstrated that the use of UHMWPE withoutadditional lubrication reduces frictional forces as compared to the useof other cable material types such as steel. As a result, the reducedfrictional load on the UHMWPE/coil tube configuration translates into asubstantial reduction of the actuation forces required to steer theendoscope. In addition, the interior of the cable housing or coil tubemay also be made of or have a coating of material to further reduce thefriction between the UHMWPE cable and the housing.

Replacement of Steel Cables with Braided UHMWPE

Through extensive testing of various materials, it was found thatbraided UHMWPE purchased under the trade name of either Spectra® made byHoneywell in the United States or Dyneema® made by DSM in theNetherlands could substantially reduce the forces required to actuatethe steerable segments of an endoscope. Additional details of thephysical properties of UHMWPE are available in commercial references.Additional details are available via the Honeywell and DSM websites. Thelubricity of the material allows it to be used without the need forlubrication in the coil tube resulting in more reliable forcetransmission elements with longer intervals between required servicingas compared to conventional steel cables. The resulting lower force alsosolves the problem of buckling the coil tubes. The construction of thepre-stretched, high denier braid of UHMWPE contributes to minimizing thelost motion in the system.

Method of Threading Braided UHMWPE through Coil Tubes

One challenge to overcome when attempting to use a braided material toreplace the conventional steel cable is the means of threading the limpbraid through a coil tube. In some cases the coil tube may be as long as110 inches and have an inside diameter of 0.025 inch.

This problem was solved in a novel way by first joining a lead line ontothe braid. The addition of the lead line allowed the braid to bemaneuvered through the coil tube. The method included bonding one end ofa lead line to one end of a multi-strand non-metallic braid whilemaintaining the diameter of the bonded area the same as or less than thediameter of either the non-metallic multi-strand braid or the lead line.Once bonded with a diameter small enough to traverse the coil tubewithout undue friction, the lead line was used to advance themulti-strand non-metallic braid through the coil tube.

The lead line could be anything joined to the braid to assist inthreading the braid structure into the tube. In one case, the lead lineto assist in braiding was a monofilament line joined to the end of theUHMWPE braid. In one embodiment, the lead line is formed from the samematerial as the non-metallic multi-stranded braid.

This monofilament line could then be threaded through the coil tube andused to pull the UHMWPE braid through as well. This method requiredbonding the monofilament line to the braid without allowing the diameterof the bond to be larger than the inner dimension of the coil tube beingused. Maintaining the size of the diameter of the bonding area may beaccomplished by reducing the diameter of one end of the lead line,reducing the diameter of the non-metallic multi-strand braid or bothbefore bonding the lead line and the non-metallic multi-strand braid.FIG. 6 illustrates how the diameter of the braid (D_(b)) and thediameter of the leader (D_(l)) are the same as the diameter of thebonding area 155. Additionally, bonding channels 120 may also be sizedand dimensioned to maintain the diameter of each of these parts of thebonded structure so that will pass through a coil tube 2614. In onespecific embodiment where the coil tube had an inner diameter of 0.025inch and the diameter of the bonding area 155 was maintained at adiameter less than approximately 0.024 inch. Additional details of thischallenge are detailed below with regard to FIGS. 7A and 7B.

FIGS. 1-5 will now be used to illustrate one proposed bonding solutioninvolving a bonding fixture was designed out of blocks of PTFE (i.e.,Teflon®). Fabricating the fixture out of PTFE or other material thatwill not bond to the leader or the braid allows the bonding of theleader to the braid while being able to control the diameter of thebonding area. FIGS. 1A, 1A1 and 1B illustrate various views of thebonding fixture 105 made from complementary blocks 108A and 108B havinga plurality of bonding channels 120. FIG. 1A is an exploded view of thecomponents. FIG. 1A1 illustrated the assembled fixture 105. FIG. 1Billustrates the assembled fixture with a view of the opening 113. Theblocks are secured together using conventional means such as a bolt 110passed through opening 113 and secured by nut 112. The blocks may alsoor alternatively be secured using a vise 103 as shown in FIG. 4.

As shown in FIG. 2, a multi-strand non-metallic braid 2612 is showninserted into an assembled fixture 105. This is the first step in theplacing one end of the lead line and one end of the non-metallicmulti-strand braid into a fixture before bonding the leader to thebraid.

Next, the end of the braid may be cut to help bond to the leader andalso aid in keeping the size of the bonded area small. In oneembodiment, there is a step of cutting a strand of the multi-strandbraid before the bonding step. Alternatively, all but one strand of thebraid was trimmed approximately ¼ inch from the end using a razor bladeprior to assembling the braid in the fixture. The remaining strand isused to bond to the leader. This cut end 128 is shown sticking up fromthe fixture 105 in FIG. 2. The next step is gluing one end of the leadline to one end of a multi-strand non-metallic braid. This may beaccomplished with a drop of cyanoacrylate glue (such as commerciallyavailable Loctite 420) placed on the end of the braid 128.

Thereafter, the braid 2612 is pulled down into the fixture 105. Theleader line 150 is then placed into the same bonding channel 120 as thebraid 2612 as shown in FIG. 4. The leader 150 is advanced to meet thebraid 2612 and any excess glue is wicked away. As shown in FIG. 3A, theleader 150 may have a reduced or shaped end 152 to aid in bonding to thebraid while also keeping the bonded area diameter appropriately sized.Alternatively, as best seen in FIG. 3B, the leader 150 may have areduced shape and a textured surface 154 to aid in bonding to the braid.As can been seen, the method includes altering one end of the lead linebefore the bonding step to improve adhesion to the non-metallicmulti-strand braid.

After the, glue dries, the braid 2612 with the attached leader 150(i.e., the monofilament line in this example) is removed from the2-piece fixture as shown in FIG. 5.

Once the monofilament leader is fixed to the end of the braid as bestseen in FIG. 5, it can then be readily threaded through multiple lengthsof coil tube 2614. Each time, the end of the braid 2612 can be cut tolength and the assembly (i.e., the leader bonded to the braidedstructure) used to thread additional coils 2614. For example, themonofilament line 150 can be bonded to a 55 foot spool of braided UHMWPEthat can be used to thread more than 50 feet of coil tubes 2614. Theability to make large lengths of the braided/tube assembly will greatlysimplify the fabrication process used to make steerable instrumentsarticulated using the non-metallic braid structure.

Alternatively, bonding the leader to the braid may be accomplished usingother known bonding techniques such as thermal bonding or othertechniques known to those of ordinary skill in the art to join thematerial type of the leader onto the UHMWPE braid. One of ordinary skillwill appreciate that the bonding technique will depend on the types ofmaterial to be joined. The Beahm Split Die Thermal Bonder 220-B is acommercially available unit that may be well suited to a thermal bondingtechnique. As such, the bonding step may also include thermally bondingone end of the lead line to one end of a multi-strand non-metallicbraid.

Method of Terminating the Braided UHMWPE

While useful in reducing friction in articulation forces, the lubricityof the UHMWPE braid makes it difficult to terminate the ends of thebraid in a precise location.

One solution to the termination challenge was the realization that thebraided UHMWPE can be terminated by simply knotting it off, or usingother techniques known for securing braids of this type. As such,terminating an end of the multi-strand non-metallic braid may includeforming a knot in the multi-strand non-metallic braid.

Alternatively, the knotted end could be further secured by gluing thebraid together or other techniques to terminate the end of the line. Assuch, terminating the braid may include applying an adhesive to the knotformed in the multi-strand non-metallic braid. One cyanoacrylate usedwas Loctite® brand 420 series adhesive. Alternatively, for ease ofmanufacturing, a pigment may be added to the adhesive to provide avisual sign whether glue was applied to each knot 133. This is animprovement over clear glue that is difficult to tell if it has beenapplied to each knot. In an alternative embodiment, the adhesive appliedto the terminated end is an ultraviolet cured adhesive such as an epoxy.

One exemplary technique is the use of a stopper knot soaked in a lowviscosity, high wicking cyanoacrylate glue. The stopper knot, also knownas a double overhand knot, as well as other suitable knots are describedin a number of references.

FIGS. 7A and 7B illustrate a braid 2612 within a coil tube 2614 having aclearance 190 between the braid and the interior surface of the coiltube. The inner diameter of the coil tube and the diameter of the coiltube are also indicated. Maintaining the appropriate inner diameterclearance 190 was another challenge solved using the methods of theinvention. If the clearance 190 is too small, then the friction forceson the braid are high leading to the need for increased actuationforces. If the clearance is too large, the pulling on the braid toactuate a segment may cause the coil tube to buckle. Maintaining theproper clearance 190 is important to ensuring acceptable forcetransmission function. Consider the following specific examples for coiltubes having an inner diameter of 0.040 inch. A clearance of 0.001 inchwill result in too much friction. A clearance of more than 0.007 inchresults in buckling and herniation. The acceptable range of forcetransmission is between greater than 0.001 inch and less than 0.007inch. Coil tubes in the size range are typically needed given the numberof control cables 2612 used in the controllable instruments describedbelow (i.e., up to 64 control cables used to control a fully articulatedinstrument). Numerous manufacturing challenges related to maintaining asmall bonding area while working with small diameter braids have beensolved by the methods described herein. As such, we have found that theratio of the clearance between the multi-strand non-metallic braid andthe interior surface of the coil tube to the inner diameter of the coiltube is less than or equal to 15%.

An exemplary UHMWPE cable is shown with an articulating instrument inFIGS. 8-14. As best seen in FIG. 8, a standard 2-56 set screw 129 wasdrilled through allowing the braided UHMWPE 2612 to be passed throughthe screw 129 and terminated using the stopper knot 133. The screw 129could then be inserted in the end of a threaded carriage assembly 120that is part of a rack or connector (further described in U.S. PatentApplication Publication US 2006/0052664). The UHMWPE cable 2612 ispulled with an actuation force to activate each segment individually asdescribed below.

As detailed above, the multi-strand non-metallic braid is connecteddistally to one segment of the plurality of segments by terminating themulti-strand non-metallic braid at the desired segment. Alternatetermination methods include:

-   1. Full strength loop manufactured in one end of the braided cable.-   2. Steel crimp of adequate length, with “toothed” or rough interior    capable of holding the UHMWPE securely in place. Alternatively, a    brass crimp with a smooth interior may be used.-   3. Metal ball placed inside the hollow braid, then glued in place to    terminate.

Steerable Instruments and System Using UHMWPE

There are a number of steerable instruments available. Examples ofsteerable instruments, various control, and force transmission systemsare described in, for example, U.S. Pat. No. 6,468,203; U.S. Pat. No.6,858,005 and U.S. patent application Ser. Nos. 10/988,212 filed11/12/2004, now U.S. Patent Application Publication US 2006/0052664,titled “Articulatable Connector Device for Endoscopes ” each of which isincorporated herein by reference in entirety. The application andpatents listed above are commonly assigned with this application.

FIGS. 8 and 9 illustrate a plurality of hinged segments 2522 and amulti-strand non-metallic braid 2612 connected distally to one segmentof the plurality of segments (i.e., via knot 175) and proximally to anactuator as described below. In this illustrative portion of the system,the braid 2612 is terminated proximally at knot 133. The screw 129 isthreaded into the rack or connector 120 so that the knot is maintainedbetween the threaded connector and the rack. Not shown in this figurebut described below is a steering controller adapted to control theactuator to move the hinged segment 2522 using the multi-strandnon-metallic braid 2612. Application of an actuation force (shown byarrow in FIG. 9) to the rack 120, pulls the braid 2612 to bend thesegment 2522 as shown. Additional details of the use of the non-metallicbraided structures described herein will be appreciated throughreference to FIGS. 10-14.

FIG. 10 illustrates a schematic view of a system 1000 for moving acontrollable article 1100. A force generator under control of one orboth of a user input device 1140 and a system controller 1145 generatesforces that are used to move the controllable article 1100. The forcesgenerated by the force generator are transmitted to the controllablearticle using force connecting elements 1135 and a connector assembly1120. The controllable article may also be an articulating instrument ora bendable instrument.

A connector assembly 1120 completes the transmission of power generatedby the force generator 1110 and applied to the controllable article1100. The two portions 1125, 1130 of the connector assembly 1120 aredisengagably coupled. The connector portion 1125 is the first connectorportion or the force generation side connector. The connector 1130 isthe second connector portion or the controllable article side connectorportion. When the connector portions 1125, 1130 are in a coupledcondition, the force transmission elements 1135 are joined and forcegenerated by the force generator 1110 is applied to the controllablearticle 1100. When the connector portions 1125, 1130 are not coupled,the connector portion 1130, force transmission elements. 1135 and thecontrollable article 1100 may be removed, in some embodiments as asingle integrated unit, from the connector portion 1125, forcetransmission elements 1135 and the force generator 1110 or actuators1115. The force transmission element 1135 may be a non-metallic braidedcable such as the UHMWPE cable described herein.

The connector assembly 1120 provides the ability to quickly connect anddisconnect the two portions 1125, 1130 allows a single forcetransmission portion to be used with multiple controllable articles.Currently, articulating instruments such as, for example, endoscopestypically have only 4 cables to provide limited control at the tip ofthe endoscope. Moreover, the connector provides compact organization andefficient coupling of numerous force transmission elements used byhighly maneuverable controllable articles. The controllable articlesdescribed herein may use 16 or more UHMWPE control cables or 4 UHMWPEcontrol cables per segment and 4 or more segments. In one embodiment,there are 32 UHMWPE cables used to control a fully segmentedcontrollable instrument. In another embodiment, there are 64 UHMWPEcables used to control a fully segmented controllable instrument.

FIG. 11 illustrates a perspective view of a connector assembly 110according to one embodiment of the present invention. The connectorassembly 110 includes a first connector portion 112 (not shown butwithin housing 109) and a second connector portion 114. The firstconnector portion 112 is within the housing 109. The second connectorassembly 114 includes a plurality of guide ways 118 each containing acarriage assembly 120. Each carriage assembly contains one or more thanone engaging feature 122. Engaging features 122 on carriage assemblies120, in the second connector portion 114 are adapted to engage with theengaging features 122 on carriage assemblies 120 of the first connectorportion 112. One end of the carriage assemblies is connected to forcetransmission elements or UHMWPE cables 130. In the illustratedembodiment, the cables are Bowden cables. The cables run through a slackarea 116. The slack area 116 allows added space for cable slack that maybuild up during controllable article movement. Thereafter, the UHMWPEcables are terminated and connected as desired to a specific segment ofthe controllable article.

The housing 109 provides a structural base for supporting the connectorassembly 110. In this embodiment, the first connector portion 112 (notshown) is secured within the housing 109. The first connector portionand its carriage assemblies are connected via force transmissionelements 130 to actuators 105. While four actuators 105 are illustrated,it is to be appreciated that more actuators may be used to drive acorresponding number of carriage assemblies. The housing 109 alsoprovides a opening 107 configured to receive the second connectorportion 114. Optionally, either one or both of the opening 107 or aportion of the second connector portion 114 may be keyed to ensurecorrect orientation prior to connection. When the second connectorportion 114 is placed within the opening 107, the first and secondconnector portions 112, 114 are brought into engagement using anappropriate quick release mechanism, such as for example a cam actuatedlever or other engagement device as known to those of ordinary skill inthe art. When the first and second connector portion 112, 114 areengaged, forces generated by actuators 105 are transmitted to thecontrollable article.

FIG. 12 shows an embodiment where the controllable instrument is atendon driven endoscope 2510. The endoscope 2510 has an elongate body2512 with a manually or selectively steerable distal portion 2516, anautomatically controlled portion 2520, and a flexible and passivelymanipulated proximal portion 2514, which may be optionally omitted fromthe device. The steerable distal portion 2516 can be articulated by hand(i.e., using mechanical force of a conventional endoscope manualcontrols adapted to articulate segments) or with mechanical assistancefrom actuators pulling on UHMWPE cables. In addition, some embodimentsallow a user to input steering commands (i.e., via a joystick 2544 orother input device) into a controller that translates the steeringcommands into endoscope segment movement.

The automatically controlled portion 2520 is segmented, and each segmentis capable of bending through a fill range of steerable motion. Thedistal portion 2516 is also a controllable segment. A more detaileddescription on the construction and operation of the segmented endoscopemay be found in U.S. patent application Ser. No. 10/229,577 filed Aug.27, 2002, which is incorporated herein by reference in its entirety.Additional details of the arrangement of components are illustrated inFIG. 13 that illustrates an actual embodiment of a computer controlledendoscope and system described herein.

Returning now to FIG. 12, the selectively steerable distal portion 2516can be selectively steered or bent up to, e.g., a full 180 degree bendin any direction 2518, as shown. A fiber optic imaging bundle 2534 andone or more illumination fibers 2532 may extend through the body 2512from the proximal portion 2514 to the distal portion 2516.Alternatively, the endoscope 2510 may be configured as a video endoscopewith a miniaturized video camera, such as a CCD or CMOS camera,positioned at the distal portion 2516 of the endoscope body 2512. Theimages from the video camera can be transmitted to a video monitor by atransmission cable or by wireless transmission where images may beviewed in real-time and/or recorded by a recording device onto analogrecording medium, e.g., magnetic tape, or digital recording medium,e.g., compact disc, digital tape, etc. LEDs or other light sources couldalso be used for illumination at the distal tip of the endoscope.

The body 2512 of the endoscope 2510 may also include one or more accesslumens 2528 that may optionally be used for illumination, fibers forproviding a light source, insufflation or irrigation, air and waterchannels, and vacuum channels. Generally, the body 2512 of the endoscope2510 is highly flexible so that it is able to bend around small diametercurves without buckling or kinking while maintaining the variouschannels intact. When configured for use as a colonoscope, the body 2512of the endoscope 2510 may range typically from 135 to 185 cm in lengthand about 13-19 mm in diameter. The endoscope 2510 can be made in avariety of other sizes and configurations for other medical andindustrial applications.

The controllable portion 2520 is composed of at least one segment 2522,and preferably several segments 2522, which are, controllable via acomputer and/ore electronic controller 2540 located at a distance fromthe endoscope 2510. Each or at least a majority, of the segments 2522may have UHMWPE force transmission elements or tendons mechanicallyconnected to force generators or actuators to allow for the controlledmotion of the segments 2522 in space. The actuators driving the UHMWPEtendons may include a variety of different types of mechanisms capableof applying a force to a tendon, e.g., electromechanical motors,pneumatic and hydraulic cylinders, pneumatic and hydraulic motors,solenoids, shape memory alloy wires, electronic rotary actuators orother devices or methods as known in the art. The linear translation ofthe actuators within the controller may be configured to move over arelatively short distance to accomplish effective articulation dependingupon the desired degree of segment movement and articulation. Themovement of the actuators may be measured using sensors to provide inputto the control system.

Each segment 2522 preferably defines at least one lumen runningthroughout to provide an access channel through which wires, opticalfibers, air and/or water channels, various endoscopic tools, or anyvariety of devices and wires may be routed. A polymeric covering, orsheath, 2530 may also extend over the body of the endoscope 2512including the controllable portion 2520 and steerable distal portion2516. This sheath 2530 can preferably provide a smooth transitionbetween the controllable segments 2522, the steerable distal portion2516, and the flexible tubing of proximal portion 2514.

A handle 2524 may be attached to the proximal end of the endoscope. Thehandle 2524 may include an ocular connected to the fiber optic imagingbundle 2534 for direct viewing. The handle 2524 may otherwise have acable 2552 for connection to a video monitor, camera, e.g., a CCD orCMOS camera, or a recording device 2550. The handle 2524 may beconnected to an illumination source 2536 by an illumination cable 2538that is connected to or continuous with the illumination fibers 2534.Alternatively, some or all of these connections could be made at thecontroller 2540. luer lock fittings 2526 may be located on the handle2524 and connected to the various instrument channels.

The handle 2524 may be connected to a motion controller 2540 by way of acontroller cable 2542. A steering controller 2544 may be connected tothe motion controller 2540 by way of a second cable 2546 or it mayoptionally be connected directly to the handle 2524. Alternatively, thehandle may have the steering control mechanism integrated directly intothe handle, e.g., in the form of a joystick, conventional diskcontrollers such as dials, pulleys or wheels, etc. The steeringcontroller 2544 allows the user to selectively steer or bend theselectively steerable distal portion 2516 of the body 2512 in thedesired direction 2518. The steering controller 2544 may be a joystickcontroller as shown, or other steering control mechanism, e.g., dualdials or rotary knobs as in conventional endoscopes, track balls, touchpads, mouse, or sensory gloves. The motion controller 2540 controls themovement of the segmented automatically controlled proximal portion 2520of the body 2512. This controller 2540 may be implemented using a motioncontrol program running on a microcomputer or using an applicationspecific motion controller.

The actuators applying force to the tendons may be included in themotion controller unit 2540, as shown, or may be located separately andconnected by a UHMWPE control cable. The UHMWPE tendons controlling thesteerable distal portion 2516 and the controllable segments 2522 extenddown the length of the endoscope body 2512 and connect to the actuators.FIG. 3 shows a variation in which the UHMWPE tendons may pass throughthe handle 2524 and connect directly to the motion controller 2540 via aquick-release connector 2554. In this embodiment, quick releaseconnector 2254 could be any of the above described connector orengagement assemblies. In this variation, the UHMWPE tendons may be partof the control cable 2542, although they could independently connect tothe actuators, so long as the actuators are in communication with thecontroller 2540.

An axial motion transducer (also called a depth referencing device ordatum) 2548 may be provided for measuring the axial motion, i.e., thedepth change, of the endoscope body 2512 as it is advanced andwithdrawn. The depth referencing device 2548 can be made in manypossible configurations. For example, the axial motion-transducer 2548in FIG. 3 is configured as a ring 2548 that may surround the body 2512of the endoscope 2510. The axial motion transducer 2548 is preferablyattached to a fixed point of reference, such as the surgical table orthe insertion point for the endoscope 2510 on the patient's body. Depthreferencing device 2548, and different examples thereof; as well assegment articulation and cable operation are described in further detailin U.S. patent application Ser. No. 10/229,577 filed Aug. 27, 2002,which is incorporated herein by reference in its entirety.

FIG. 14 shows a partial schematic representation of a single UHMWPEtendon coupled to a segment. For clarity, the other parts of a completeendoscope, including other tendons and segments, have been omitted fromFIG. 4. Tension applied to a UHMWPE cable is transferred across theentire segment, resulting in bending. The Bowden cable 2610 has a coiltube 2614 attached to the base 2622 of the segment 2601 and also fixedat the proximal actuator end 2603. The UHMWPE cable 2612 is connected tothe actuator 2605 and the distal segment end 2630. By applying tensionto the UHMWPE cable 2612, only the intended segment 2601 is bent, andmore proximal segments are unaffected. The UHMWPE cable 2612 is placedin tension by the actuator 2605, which is show in this variation, as amotor pulling on the UHMWPE cable 2612.

While numerous embodiments of the present invention have been shown anddescribed herein, one of ordinary skill in the art will appreciate thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to these embodiments of the inventiondescribed herein may be employed in practicing the invention. It isintended at the following claims defined the scope of the invention and,it methods and structures within the scope of these claims and theirequivalents be covered thereby.

1-15. (canceled)
 16. A system, comprising: an actuator; a steerableinstrument, comprising a plurality of hinged segments, each segmentbeing articulable with respect to another segment, and a multi-strandnon-metallic braid having a distal end portion connected to one segmentof the plurality of segments and a proximal end portion connected to theactuator, and a coil tube disposed between the actuator and the onesegment, wherein at least a portion of the multi-strand non-metallicbraid extends through the coil tube; a lead line for attachment to themulti-strand non-metallic braid and configured to thread thenon-metallic braid through the coil tube; and a steering controlleradapted to control the actuator to move the hinged one segment using themulti-strand non-metallic braid.
 17. The system of claim 16 furthercomprising; a connector assembly, wherein the proximal end portion ofthe multi-strand non-metallic braid is attached to the connectorassembly and the connector assembly couples the multi-strandnon-metallic braid to the actuator.
 18. The system of claim 17, whereinthe connector assembly comprises a carriage assembly.
 19. (canceled) 20.The system of claim 18, further comprising: a threaded element on theproximal end portion of the multi-strand non-metallic braid to attachthe proximal end portion of the multi-strand non-metallic braid to thecarriage assembly.
 21. The system of claim 20, further comprising: aknot formed in the multi-strand non-metallic braid positioned betweenthe threaded element on the proximal end portion of the multi-strandnon-metallic braid and the carriage assembly.
 22. The system of claim16, further comprising: a knot formed in the multi-strand non-metallicbraid.
 23. The system of claim 22, further comprising: an adhesiveapplied to the knot formed in the multi-strand non-metallic braid. 24.The system of claim 23, wherein the adhesive applied to the knotcomprises a pigment that provides a visual indication that of theadhesive.
 25. (canceled)
 26. The system of claim 16, wherein the ratioof a distance between the multi-strand non-metallic braid and aninterior surface of the coil tube to an inner diameter of the coil tubeis less than or equal to 15%.
 27. The system of claim 16, the distal endportion of the multi-strand non-metallic braid is connected to the onesegment of the plurality of segments by terminating the multi-strandnon-metallic braid at the desired segment.
 28. The system of claim 16,wherein one end portion of the lead line is bonded to one of the distalend portion and the proximal end portion of the multi-strandnon-metallic braid to define a bonded region, and a diameter of thebonded region is the same as or less than a diameter of both the leadline and a diameter of the multi-strand non-metallic braid.
 29. Thesystem of claim 28, wherein at least one of a diameter of the one endportion of the lead line and a diameter of the one end portion of themulti-strand non-metallic braid is smaller than the diameter of the leadline and the diameter of the multi-strand non-metallic braid,respectively.
 30. The system of claim 28, wherein the diameter of thebonded region is the same as or less than an inner diameter of the coiltube.
 31. The system of claim 28, wherein the one end portion of thelead line has a textured surface.
 32. The system of claim 16, whereinadjacent segments of the plurality of segments are connected via a hingeand are articulable with respect to one another about the hinge.